At Structural Anchor Supply, we are proud to sell the products required to install Helical Pulldown™ Micropiles from CHANCE®. This affordable solution allows the Chance® installer to be able to double the capacity of a bare installation in some soil profiles.
Helical Pulldown™ Micropiles are ideal for use for support of a new structure on a poor soil profile, underpinning an existing structure, or supporting structural loads on a limited access site. Not only are they high capacity, installing them is a process that is more simple than you might have imagined. Below is a general step-by-step overview of how helical Pulldown™ micropiles from CHANCE are installed:
Step 1: The first screw pile length (lead section) is placed upright at the desired installation location. The helical pier is then “screwed” into the ground by rotating it with a hydraulic torque motor mounted on a heavy equipment vehicle featuring a digital torque indicator – applying the needed hydraulic pressure that twists it deep into the soil below.
Step 2: Plastic piping or a similar material is then placed around a hole at the base of the pile (this will later be used for creating a grout reservoir). Next the crew will add an extension shaft and displacement plate at the base of the screw pile – securing it by adding a bolt.
Step 3: The crew will then create the grout reservoir, pouring wet grout into the hole and around the base of the pile.
Step 4: The hydraulic torque motor will once again be utilized to screw the next extension with the newly added displacement plate into the soil – creating a void in the soil below that’s quickly filled in by grout from the reservoir above. Once hardened, the surrounding grout helps stabilize the shaft of the helical pier.
Step 5: The crew will then add new extension shafts and displacement plates – utilizing torque up to the point when the helical bearing plates come in contact with the bearing soil. In the last three feet, as usual, the installation torque is measured to correspond with the ultimate capacity.
Now that we’ve discussed the installation process, in part 2, we’ll go into detail regarding the advantages that helical pulldown micropiles have over other foundation systems.